[Clinical study on the relationship between the displaced fracture of the inferior ramus of pubis and the posterior pelvic ring injury].

OBJECTIVE: To investigate relation between displaced inferior ramus fractures and posterior pelvic ring injury.

METHODS: From August 2012 to August 2015, 51 patients of pubic ramus fractures with complete record were retrospective reviewed including 27 males and 24 females with an average age of(49.1±19.0) years old ranging from 9 to 90 years old. The time from injury to treatment ranged from 0.3 to 48 hours with an average of 10.1 hours. According to Tile classification of pelvic fractures, 28 cases were type A, 17 cases were type B, 6 cases were type C. Pelvic radiographs and computed tomography scans were detailed and evaluated for whether there were posterior pelvic ring injury, meanwhile pubic rami fractures were divided into 4 groups as follow: displaced inferior ramus fractures group, undisplaced inferior ramus fractures group, displaced superior ramus fractures group, undisplaced superior ramus fractures group;the incidence rate of association of posterior pelvic ring injury was determined and compared.

RESULTS: Twenty-six patients had displaced inferior ramus fractures, all of them (100%) were combined with posterior pelvic ring injury. Twenty patients had undisplaced inferior ramus fractures, 6 of them(30%)were combined with posterior pelvic ring injury. Twenty-eight patients had displaced superior ramus fractures, 22 of them(78.5%) were combined with posterior pelvic ring injury. Twelve patients had displaced superior ramus fractures, 5 of them(41.6%) were combined with posterior pelvic ring injury. Compared with undisplaced inferior ramus fractures group, there was statistic difference( P =0.028 8<0.05) on the incidence rate of posterior pelvic ring injury, there were no statistic difference( P =0.055 8>0.05; P =0.168 3>0.05) while compared with other undisplaced superior ramus fractures group and displaced superior ramus fractures group, but the incidence rate of association with posterior pelvic ring injury much higher than both of two groups (100% vs 41.6%, 78.5%).

CONCLUSIONS: Displaced inferior pubic ramus fractures have the highest incidence rate of association with posterior pelvic ring injury, frequently prompted injury to the posterior pelvis. Displaced inferior ramus fractures were an indirect evidence of posterior pelvic injury.